Means for controlling alternating-current motors.



PATENTED AUG. 28, 19.06.

, P-.-EIGHBERG. MEANS FOR-CONTROLLING ALTERNATING GURRENT MOTORS.

APPLIOAT ION FILED JANJI. 1905.

w'rlfnesges.

from the secondary of a transformer, the pm- UNITED STATES FRIEIHHGH EIUHBERG, OF BERLIN,

PATENT was.

'GERMANY, ASSIGNOR TO GENERAL E EURIO COMPANY, A CORPORATION OF NEW YORK.

To all 1071/0711 it may concern:

Be it known that l, FRIEDRICH EIGHBERG, a subject of the Emperor of Austria-Hungary, residing at Berlin, in the Empire of Germany, have invented certairrnew and useful Improvements in Means for Controlling Alten. hating-Current Motors, of which the following is a specification.

My invention relates to the control of vehicles propelled by alternating current motors of the commutator type in which current is supplied tothefield windin'g while the armature is n'iaintained in a locally-closed circuit in which current is induced by current in the field-circuit. I

My invention is thus applicable to the control of motors of the type disclosed in an application, Serial No. 146,692, filed by Gabriel Winter and myself March 7, 1903. In this former application a type of motor is disclosed in which the armature of the motor is provided with two sets of commutatorbrushes. One set is connected to short-circuit the armature on the line of field magnetization, so that the armature-winding acts as a short-circuited secondary for the fieldwinding, thereby increasing the power factor and efficiency of the motor, while the second set, displaced substantially ninety elec tricahdegrees from the first set, is supplied mary of which is in series with the field, with current which produces a magnetization of the armature at an angle to that produced by the currents in the field-winding and the short-circuiting armature connection and which with these currents produces the motor torque.

My present invention consists in a simple and efiicient means for the control of a plurality of such motors, comprising a controlswitch adapted to connect the field-windings of the motors in series and in parallel. The controlsswitch may further be arranged to vary the number of field turns of the motor. Since the armature connections are not changed, the controlling switch is eXceed,

ingly simpleand since no resistance is employed an eflicient operation is secured.'

Myinvention will be best understood by reference to the accompanying drawing, which shows diagrammatically two motors provided. with a controlling-switch arranged in accordance with the invention.

Specification of Letters Patent.

Patented Aug. 28, 1906.

Application filed January 11, 1905- Serial No. 240,552.

In the drawing, F represents the fieldwinding of one of the motors, and A the armature. The armature A is provided with one set of brushes 1) b, short-circuiting the armature on the line of magnetization of the field-Winding. The second set of brushes 1) b is supplied with current from the secondary of the transformer S, the primary of which is in series with the field-windings. The second motor is similarly arranged, its corresponding brushes 1) I) being connected m series with those of the first motor. A re versing-switch R is provided for varying the relative connections of the two armatures to the series transformer, and thereby reversing the direction of torque of the motors.

C represents the controlling-switch by means of which the field connections are varied.-

The controlling-switch C is shown with its contacts developed on' a plane surface and in off position. When the COIltIOlliIlg-,'

ground. The two fields are thus connected in series with all the field-windings in circuit. When the controlling-switch C is moved to its second position, the circuit is closed, as follows: from trolley T, contact 0, contact o through a portion offield F", contact a contact a, a portion of field F, to series transformer S, and portions of both fields are thus cut out of circuit and the speed of the motors is increased. lVhen the controller C is moved to its third position, the two fields are connected in parallel with all the field-windings in circuit, as will be seen by tracing out the circuits, and in the fourth position of the controlling-switch the number of field turns is again reduced. Four speeds are thus obtained with a simple arrangement of the controlling-switch and without the employment of resistances. ries transformer S arranged. with a variable ratio'of transformation, so that a further control of the motor speed and torque may be obtained, if desired.

Vlhlle for the sake of simplicity l have shown the motors diagrammatically, it will be understood that any well-known form of f eld F, primary of series transformer S, to

l: have shown the seriphery of a laminated iield structure, while the armature ould be provided with a winding similar to that in a direct-current inachine.

.l have shown the motors in the drawings provided with two independent sets of brushes; but'I wish it to be understood that this particular arrangement of brushes and collliCCilOllS is not essential, it being necessary only that the brushes and their connections should be arranged both to short-circuit the armature on the line of iield magnetization and to supply current to the armature on a line displaced substantially ninety degrees from the field magnetization.

(hanges may be made in the arrangement of the control-switch and the circuit connections, and fH'C-OIillhQlY l-do not desire to limit mysel l to 1 he particular construction and arrangement ol' parts here shown, but aim in the appended claims to cover all modifirations which are within the scope of my in- 'enti'on.

W'hat l claim as new, and desire to secure by Letters Patent oi the United States, is

1. In combination with a plurality of alteruating-current motors ol the connnutator type having their armatures connected in a locallywlosed circuit, means for varying the relative connections of the niotordields to the. source of current and for varying the number ot etl ective 'lield turns.

2. In combination with a plurality of alternating-current motors of the commutator type having their armatures connected in a locally-closed circuit, a switch adapted to connect the motor-fields in series and in parallel to the source'and to vary the number of ell'ective [ield turns.

3. In combination with a plurality of alternatinc-current motors of the commutator type each having coinmutator-brushes and connections arranged both for short-circuitin; the armature on the line of field magnetis nation and for supplying current to the armature on a line displaced substantially ninety electrical degrees therefrom, a translormer having its secondary in closed circuit with the armattire-supply connections and its primary ins'eries with the motor-fields,

and a switch adapted to connect the motorlields in series and in parallel to the source of current.

' In combination with a plurality of alternating-current motors of thecommutator type each having cornnn1tat n'-b: .i hes and connections arranged both tor slmrt-circuitnu; the armature on the line ol'lield magnetization and for supplying current to the an mature on a line displaced substantially ninety electrical degrees therefrom, a trans former having its secondary in closed circuitarmaturesupply connections and its pri-- mary in series with the motor-fields, and a switch adapted to connect the motor-fields in series and in parallel to the source and to vary the number of effective field turns.

6 'In combination with a lurality of alternating-current motors of t e commutator type each having brushes. and connections arranged both tor short-circuiting the armature on the line of lield'magnetization and for supplying current to the armature on a line displaced substantially ninety electrical degrees therefrom, a transformer having its secondary included in closed circuit with the armature-supply connections and its primary in series with the motor-fields, a switch adapted to connect the motor-fields in srries and in parallel to the source and to vary the number ot'e'tl'ectivc field turns, and a switch adapted to reverse the relative connections of the secondary of saidatransformer to the armature-brushes.

7. In combination with a plurality otalternatinQ-currcnt motors of the connnutator type each having brushes and connections arranged both for short-circuiting the armature on the line of lield magnetization and for supplying current to the armature on a line displaced substantially ninety electrical degrees therefrom, a transtorlner havine its secondary included in closed circuit with the armature-supply connections and its primary in series with the motor-fields, a switch adapted to connect the motor-fields in series and in parallel to the source and to vary the number of ell'cctive turns, and ineans l'or varying the ratio of transtorination ot said transformer.

In witness whereof I have ln-reunto set my hand this 21st day of December, 1904.

FRIEDRICH EKIIBERG.

Witnesses llnxnr llixsrnn, Woumnui lIALTP'l.

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